End of Empiricism
by GanHOPE326
Summary: Having defeated Aizen, Ichigo finds himself confronting a far more insidious opponent - a philosophical dilemma.


**End of Empiricism**

The last sparks of Urahara's kidou died down and disappeared. Ichigo was standing in the middle of the battlefield, alone, victorious, exhausted. He drew in breath - the air was painful through his lungs, beaten by so much fighting at such an extreme level. He could feel each muscle in his body crunch and stiffen, ready to scream in pain, as not only the adrenaline, but his very spiritual powers abandoned his body, after burning fiercer than ever for one last time.

It was over.

After all that time, so much death, so much pain, it was over.

Urahara walked to him, slowly clapping. With his quirky getup and smirk, one could have almost thought his gesture sarcastic.

"Congratulations, Mr. Kurosaki." he said. "You finally did it. I always had the utmost trust in your abilities."

Ichigo nodded, still panting, without even as much breath as needed to speak. His eyes were blurred and his mind desperately craved some rest, but he could not allow it yet. It was an automatic habit now, drilled down by both trainers and enemies on the battlefield; never let your guard down when it seems the most appropriate. There was always one last trick, one more transformation. And this enemy had truly been deserving of his title of Death God. Sousuke Aizen had been an omnipotent force of destruction, unsurmountable in single combat, endlessly cunning and deceitful outside. It seemed almost unreal that he _could_ be defeated at all.

In fact, it didn't make sense.

"This is an illusion." he said, matter of factly. He gripped his sword tighter, tried to rise it up to a guarding position. Fuck, the damned thing was so heavy.

Urahara was surprised, was on guard for a moment, then relaxed and laughed. "I understand what you mean, Mr. Kurosaki. But I believe you are being overly suspicious. For once, let yourself taste the joy of victory - Aizen has been truly brought down."

"How can you tell?" Ichigo's eyes shifted quickly across the landscape, looking for any discrepancy that could reveal the concealed enemy. "It's his oldest and best trick. Yet he never used it during the hardest fight he ever fought. Why would he do that? He must have kept it for last."

"Perhaps he considered such sneaky things beneath his current might." answered the scientist, shrugging. "But if he was using it, searching for him with your sight would be absolutely pointless. His illusions aren't the camouflage of a chamaleon - they run far deeper than that."

"Then how would I fight him?"

"You wouldn't." said Urahara, plainly. "If he managed to impress Kyouka Suigetsu's release upon your eyes, he would have won. Without control over your senses, you would be forever severed from reality. Do you remember ever seeing that release?"

Ichigo relaxed. "No. I don't." he admitted, finally.

"There you go, then. Give me a minute to wrap up here, then we can go meet your friends again."

Urahara went to the place where Aizen had last stood - to collect the tiny marble of reiatsu his last kidou had trapped him into. Ichigo sat on the ground, leaning on Zangetsu to stop himself from collapsing altogether.

"Bankai!" he exclaimed, suddenly. Urahara jumped back and put his guard up before realising there was no danger.

"What goes through your mind now, Mr. Kurosaki?" he exclaimed, alarmed. "Surely you don't want to die of reiatsu exhaustion at this point."

"No, sorry, sorry!" said Ichigo. "I meant, Aizen's bankai. He never showed it to us. Yet he was a captain, he couldn't have become one without achieving it."

"Perhaps he really never had bankai." suggested the scientist, after collecting his hat and composing himself. "After all, with his illusions, he could have easily convinced any examination commission that he had one. It would not be unprecedented. Zaraki Kenpachi is very powerful too, yet he does not possess even a shikai."

"Perhaps." the boy shook his head. "But what if instead he had it, and it was an even more powerful version of his shikai? Like Byakuya's, or Renji's, or... you know."

"More powerful?" Urahara was amused. "Why, how powerful would that even be? Kyouka Suigetsu was already almost almighty."

"It could be able to create illusions even _in your past_." suggested Ichigo. "Not just confuse your senses, but your memory as well. Rewrite it. Make you forget that you ever saw... _that's it!_ I've seen Kyouka Suigetsu's shikai at some point, _I just don't remember it!_ "

The scientist's expression darkened. "Mr. Kurosaki," he said, "that is quite a dangerous rabbit hole you are falling down into. Suppose that we accepted your hypothesis - that there exists a power able to interfere with all your senses, building perfect illusions, without leaving any trace in your memory because it can rewrite those as well. How would you go about proving, at any given moment, that you are _not_ a victim of such a power?"

"Well..." Ichigo thought for a while, and was almost about to speak before stopping himself. He raised his hand, then let it fall down his side. "Damn." he concluded.

"Precisely." Urahara nodded. "There is no solution. You could not test your hypothesis in any way. Suppose you see empty air where a rock should be - if it was just a visual illusion, you could go and smash your head against it, and if you feel pain, you would know there really is a rock. But this is perfect illusions we're talking about. You could smash your head until it cracks open and you die, and you wouldn't feel a thing until it's too late."

"But then you would see me die with my head in mid-air." suggested Ichigo.

The other laughed. "Mr. Kurosaki, in that scenario, _I would not be a person_. I would just be a figment of your imagination, another element of the illusion. You could trust nothing and nobody. It would just be you and your own mind, alone, in the middle of a fake universe. As your human philosopher Descartes put it, _cogito ergo sum_ : your only certainty would be that you, yourself, exist and think."

"Yeah, but this Descartes did not have to fight friggin' Sousuke Aizen."

"Perhaps he had his own battle, Mr. Kurosaki. Against an enemy not any less scary." Urahara stared at the horizon, bemused. "He considered whether there could not be a demon deceiving us at all times, preventing us from seeing the truth - a similar, if more speculative, predicament to yours. Tell me: in your hypothetical Aizen bankai scenario, how would you be sure that you weren't submitted to it even _before_ knowing who Aizen was?"

"I couldn't." admitted Ichigo. "But why would that be a problem? Without Aizen, no one could create such illusions."

"That is not the belief of all. Albeit, I'll concede, it is the most practical."

Extending one hand, the scientist pulled Ichigo up, and lent him his own shoulder, since he could barely stand.

"I suggest we leave this problem to another day, and to more leisurely discussions." he said, as he whirled his cane sword and stabbed the empty space in front of him. A luminous fissure opened - a Senkaimon leading back to the human world. The black butterfly that was the silent guide for every Death God going back and forth fluttered to his head. "I live by the creed that it is smart to ask the questions that can be answered, and wise to not ask the ones that can never be. To you, Mr. Kurosaki, I suggest to enjoy a nice meal, a pleasant hot bath, and the company of your friends. None of that will feel any less real than it would at any other time. And I think the pretty girl with the light brown hair feels more than simple friendship for you - maybe you'd like to explore that."

Ichigo laughed. "Who, Orihime? Come on, don't joke around."

"I would never, Mr. Kurosaki."

The boy drew breath. Yes, perhaps he was being too anxious. And after all, nothing had happened - no surprise attack had stabbed him. He could relax. He needed it. He deserved it.

"One thing," he asked, "that Descartes guy - how did he solve his demon problem?"

"He never did." said Urahara. "In a very human fashion, what he came up with was not a solution, but a plea. He decided that God could not possibly be so cruel as to create such a deceitful, unescapable demon."

He rolled the Aizen marble between his fingers.

"I will let you draw you own conclusions, Mr. Kurosaki, as to whether he was right about that."

* * *

 _Shine a light on the back of the cave,_

 _and fill in the hollow core of the world._

 _Smother the senses in the kindly veil of Maya,_

 _Bankai: Kyouka Suigetsu, Mugen Kagami [Mirror Flower, Water Moon: Infinite Mirror]._

They were all standing against a single long wall in the Central 46, immobile, with empty eyes fixed onwards. Like statues of soldiers guarding an ancient Emperor's tomb, the entire Gotei 13, the exiles, and the human invaders. Sousuke Aizen and his two aides - Gin Ichimaru and Kaname Tousen - walked in front of them, reviewing their ranks.

"Is this necessary?" asked Tousen. "Every day?"

"Not strictly." said Aizen. "I don't believe the Infinite Mirror can possibly break. But this is the first time I use it for so long on someone. Besides, I feel like I owe it to them. Just because they were defeated... easily, does not mean I should not respect their bravery in some way."

"Truth is, you're the sentimental type, captain." commented Gin, with a slimy smile.

Aizen responded with his own, far more sincere. "Guilty as charged, I'll confess."

Tousen came close to one of the hypnotised enemies - the orange haired boy, half-human, half-god. What a pitiful effort his had been - just a few days of training and a lot of guts against enemies refined by centuries, millennia of fighting with the sword and the magic arts. Had it not been for Aizen bringing an end to the war, and Soul Society in its entirety, in one fell swoop, he would have surely fallen to the sword of one of the captains. He touched the boy's forehead. It was still warm, with no trace of sweat. The breath was regular. Coursing his hand across his face, he could feel his expression. Serene, peaceful. Happy, even.

"You promised, Aizen." said the blind captain, quietly. "When?"

"I do not need your help any more. I will keep my word, don't worry." Aizen patted his follower's shoulder, amicably. "As soon as we figure out how to solve your little... technical issue. Such an arbitrary restriction, really, that you ought to _see_ it... what is special about sight? What makes it so much more _real_?"

"I do not know." commented Tousen.

"Of course." said Aizen. "Caprices of the zanpakuto, I guess. They do not necessarily follow what we would call logic. But with the Hogyoku in my hands, it should not be a hard matter to solve."

"I can't figure out why would you want to join them." Gin shrugged. "You're one of the few to escape this thing. Enjoy the real world with us!"

Aizen shook his head. "I understand that all too well. Just because we're born in one world, does not mean we must be stuck in it if it does not please us. I am trying to escape mine by changing it. Tousen has a faster, easier way at his disposal - I do not blame him for wanting to take it. In fact, I was the one who offered it to him."

Gin laughed. "Good thing I'm happy in this world, then. The real one."

"Maybe that you're happy in such a pit of misery and suffering says something about _you_."

"As you say, captain. Never tried to hide what I am. As long as I'm the one inflicting the misery rather than on the receiving end, I'm pretty fine." said the other. "But what about you? You're the one who decided to wage war on this entire world, yet you seem to think yourself as doing _good_ , even. I'm many things, but not a hypocrite, at least."

Tousen frowned at this dig, but Aizen took it in good spirit.

"Perhaps I am." he admitted. "And yet - when I look at them, I don't think so. Had I not intervened, many of them would have died, killed each other in a fratricide war over something that was not worth fighting for, stupid dusty rules to uphold."

"And that you manipulated to your advantage." reminded Gin.

"That I did." Aizen laughed. "But now, here they are. Living in a world that revolves around them - crafted to be perfectly indistinguishable from this. They'll each have their own stories, perhaps absurd, or contradictory, but happy to them. And you know, they say that the zanpakuto mirrors the most secret nature of its master. So it is not strange that I ended up wielding Kyouka Suigetsu. Because if there is something that I can remember from my earliest childhood, it's that I was never under the illusion that our world is any different from theirs."

They finished reviewing the catatonic prisoners without talking any more. The last one was Kenpachi Zaraki - the gigantic Death God towered above all three of them. One could only wonder what kind of bloody fantasy of mass slaughter his mind was living right now. His muscles seemed to be rippling with energy under his skin, and the three men almost inadvertently kept a slightly longer distance from him than the others, as if feeling that he could break out of the illusion at any moment with his brute strength and sheer savagery.

"And that wraps that up!" concluded Gin, with a clap. "What comes next, captain?"

"A number of things." said Aizen. "I was planning a trip to Hueco Mundo for us today, if you don't mind. We will harvest some of the most powerful Menos for ourselves. Not much help in battle, probably, but they could make for good lab rats for testing the Hogyoku. Once we get that working, it will be time to fix our gaze upwards."

"I do not care what happens after I got what I ask for." commented Tousen. "But I will still say - I believe your crusade to be madness."

"Madness it indeed is. To topple He who sits in the highest throne in the heavens is no joke. And yet, I will try. I believe we all have a right to a God who is just to us, and gives us what we need, when it would cost Him so little."

He launched a last glance at his defeated enemies, each lost in their own world.

"Unfortunately, we're not all as lucky as them to get one." he concluded, leaving and closing the door behind him.


End file.
